1. Field of the Invention
The present invention relates to an inventory management method, system and program for controlling amount of stock.
2. Related Art Statements
Approaches for management of inventory are divided broadly into a fixed quantity ordering system and a fixed interval ordering system, and they are well known. The fixed quantity ordering system is a system for ordering a certain quantity of a product when a stock falls below a criteria quantity. The fixed interval ordering system is a system for ordering only shortfall in a quantity being sufficient to the basic stock, periodically (e.g., each month end or each weekend).
The basic stock, which is the basics of inventory management, is derived from a possibility shipping quantity for a period from an ordering point to a time at which items are supplied (i.e. during a restock lead time) and a safety stock, which is to compensate a difference between an actual shipping quantity and the possibility shipping quantity when the actual shipping quantity during the lead time is greater than the possibility shipping quantity. In a manufacturing and logistics department, order quantities and production volumes are adjusted so that stocks can be closed to the basic stocks to coincide with them. Making more stocks improves on time delivery rates, that is we can more flexibly respond to orders or demands. On the other hand excess stocks would decrease stock turnover rates to increase inventory costs. Thus in order to increase the stock turnover rates the basic inventories must be minimized to a certain extent that the on time delivery rates slightly decline.
Consequently, some systems for effectively managing inventories have been developed. For instance, an inventory management system has been developed, this system comprises a means for simulating basic stocks based upon past anticipated requirements, actual shipments, and feature requirements plans, and means for determine how to order or selecting one of ordering systems based upon the simulation results (refer to a publication: Japanese Patent Laid Open No. 7-192068).
Conventional inventory management systems determine basic stocks based upon receipts of orders on receiving the orders. For example, in the above mentioned conventional inventory management system, when a larger quantity order having a delivery time in long term is accepted, this large quantity order's information is incorporated into a set of samples to calculate an inventory, so that this information has an great impact on a basic stock. However, a large quantity in a bulk order more considerably than an average order quantity rarely appears. If temporary information such as the bulk order is incorporated into the set of the samples to determine the basic stock, excessive working stocks are held. Thus inventory costs are raised and the inventory cannot be effectively controlled. It is an object of the present invention to provide a system, method and program for utilizing statistical techniques to effectively derive inventory information.